Stay-bolt for boilers.



B. E. D. STAFFORD. STAY BOLT FOR BOILERS. APPLICATION FILED NOV. 30.1914.

1 36,224. Patented Aug. 7, 1917.

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BENJAMIN E.-D. STAFFORD, OF- PITTSBURGH,PENNSYLVANIA, ASSIGNOR TOFLANNERY BOLT COMPANY, OF PITTSBURGH, PENNSYLVANIA.

STAY-BOLT FOR BOILERS.

Application filed November 30, 1914.

To all whom it may concern:

Be it known that I, BENJAMIN E. D. STAFFORD, a citizen of the UnitedStates, and a resident of Pittsburgh, in the county of Allegheny andState of Pennsylvania,

have invented certain new and useful Improvements in Stay-Bolts forBoilersyand I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same. H

My invention relates to an improvement in flexible stay bolts forboilers, the object being to provide a composite bolt that will be asrigid longitudinally as the ordinary bolt, but flexible laterally so asto permit the bolt. to yield or give to accommodate itself to theunequal lateral movements of the inner sheets, thereby preventingbuckling or undue straining of either sheet.

IVith this object in view my invention consists in the parts andcombinations of parts and in the details of construction as will be morefully explained and pointed out in the claims.

In the accompanying drawings, Figure 1 is a view in section of oneembodiment of my invention, and Figs. 2, 3 and 4 are views ofmodifications.

1 represents a tubular bolt the outer end 2 of which is enlarged andthreaded externally, for its attachment to the outer sheet of theboiler, and the inner or smaller end also threaded externally for itsattachment to the inner sheet of the boiler. This tube 1 is preferablymade of stay bolt metal, or a mild grade of open hearth steel, and iscorrugated as shown, the corrugations be ing either circumferential orspiral.

The head 2 is also threaded internally for the engagement therewith ofthe externally threaded head of the inner bolt 3, which is preferablysolid but much smaller in cross section than the ordinary solid staybolt. This inner bolt 3 passes longitudinally through the outer hollowbolt and is preferably welded to the inner end of the latter, andprojects beyond said inner end so that it may be upset as at 4, againstthe outer face of the inner sheet of the fire box or boiler.

With this construction the connections between the two bolt members 1and 3, are at the ends of the outer members and in the Specification ofLetters Patent.

Patented Aug. 7, 191?. Serial No. 874,828.

planes of the inner and outer sheets of the boiler, consequently therecan be no give longitudinally except such as may result from thestretching of the inner member. The two members are disconnected fromeach other intermediate their ends and it is intended that the metal inthe combined cross sectional area of the two members shall about equalthat of the metal in the single rigid bolt now in common use, but bymaking it of two parts instead of one, it will be flexible laterally andfree to give or yield under the movements of the two sheets, withoutunduly straining either and without injury to the bolt.

In the construction shown in Fig. 2 the inner end of the tubular member1 of the bolt is threaded internally, and the inner solid member 3 isprovided with a rounded head 3 which rests against the curved seat 1formed within the head 2 of the outer member 1 of the bolt, and with anexternally threaded inner end which engages the threaded end of theouter member of the bolt, for securing the two parts of the bolt againstseparation or independent longitudinal movement. The inner threaded endof the inner member 3 of the bolt, passes through the inner end of theouter member 1 and is screwed into the inner sheet, the head 2 of theouter member, being screwed into the outer sheet as in the previousconstruction. WVith this construction, the threaded connection betweenthe inner and outer section of the bolt, and the contact between head 3"and seat 1 prevent the escape of any steam through the outer member ofthe bolt.

In Fig. 3, the inner member is provided with spherical heads, one ofwhich 6 is mounted in the outer section 1 near the inner end of thelatter, while the other 3 rests against a curved seat in the head 2 asin the previous construction.

In assembling this latter bolt, the inner bolt is inserted through thehead 2, and the outer member is then shaped by suitable tools to lockthe head 6 within its seat in said outer member. The extreme inner endof the outer section 1, is reduced and threaded to engage the innersheet of the boiler.

In the construction shown in Fig. 4, the head 2 of the inner member 3 ofthe bolt, is enlarged and threaded externally to engage the outer sheet,The shank of the bolt is also provided adjacent the head 2 with athreaded section 8' to which the outer member 1 of the bolt is screwed,the inner end of said outer member being secured to the inner threadedend 3 of the bolt, the said threaded sections?) and 3 being of greaterdiameter than the shank. The outer member of the bolt, is in thisinstance merely a sleeve secured to the bolt proper and reinforcing thelatter between its ends.

In all of these constructions the shank of the bolt is in two parts, onewithin the other, the outer part being constructed to bend freely andthe inner part sustaining it longitudinally.

If desired the inner member may be provided with longitudinal slits 8 asshown in Fig. 4 which add to the flexibility of the same withoutimpairing its capacity to resist longitudinal strains.

It is evident that many slight changes might be resorted to in therelative arrangement of parts shown and described without departing fromthe spirit and scope of my invention. Hence I would have it understoodthat I do not wish to confine myself to the exact construction andarrangement of parts shown and described except as set forth in theclaims annexed.

Having fully described my invention What I claim as new and desire tosecure by Letters-Patent, is

1. As anew article of manufacture, a flexible stay bolt composed of anouter corrugated tube having an enlarged externally threaded hollow headand a bolt member within said tube and having a head within the head ofthe tube, the opposite ends of said tube and bolt member beingconnected, the said tube and bolt member being disconnected at pointsintermediate their ends so as to permit the bolt as a whole to flexlaterally.

3. In a flexible stay bolt, the combination of an outer corrugated tubehaving an enlarged head threaded externally and internally, and a boltmember within said tube and having an externally threaded head to engagethe internal thread in the head of the tube, the other end of the boltmember being welded to the smaller end of the tube.

In testimony whereof, I have signed this specification in the presenceof two subscribing witnesses.

BENJAMIN E. D. STAFFORD.

Witnesses:

EDWIN SPENCER Bron, WM. CHARLES BINGHAM.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. G.

